Beta-thiocyano ketones and method for their preparation



Patented F eb. 26, 1946 fi-THIOCYANO KETONES AND METHOD FOR THEIR PREPARATION Herman A. Bruson, Philadelphia, Pa., assignor to Riihm & Haas Company, Philadelphia, Pa., a

corporation of Delaware No Drawing. Application February 26, 1944, Serial No. 524,089

9 Claims. (Cl. 260-454) This invention relates to ketones which have a thiocyano group in the beta position in relation to the carbonyl group thereof. It also relates to a process for the preparation of said ketones.

Thiocyanation of organic compounds has heretofore been accomplished by replacement of a tures than the open-chained ketones, such ashalogen atom or of a sulfate or phosphate ester group, by addition of thiocyanogen to both sides of a multi-bonded linkage of carbon atoms, and

by addition of thiocyanic acid to certain unsatu-' rated hydrocarbons having reactive double bonds, wherein there are used inert organic solvents at relatively low temperatures. It has generally been held impracticable to work with thiocyanic acid because it polymerizes at room temperature to a yellow insoluble compound, hydrolyzes readily in aqueous solutions, and can be handled only in dilute solutions, such as ether solutions, at low temperatures.

According to this invention, thiocyanic acid is liberated in an aqueous medium and is immediately reacted with an n p-unsaturated ketone at a temperature above room temperature (about 25-30 C.) up to about 100 C., under which conditions and at which temperatures the rate of addition of thiocyanic acid to the reactive ketone system is greater than the rate of polymerization and/or hydrolysis of thiocyanic acid. While such a procedure is apparently contrary tothe holdings of the prior art, even at 90-100 C. and in the presence of water only traces of polymer, if any, are encountered and very little hydrolysis results. Even in those cases where extreme susceptibility to cleavage would be expected, as, for example, in the case of B-tert. thiocyano ketones, good yields of the fi-thlocyano product are obtained.

The process disclosed herein is applicable to a wide. variety of cyclic and acyclic ketones having an olefinic linkage in a position which is czfi to the carbonyl group. More than one such double bond may be present in the ketone. The

such as vinyl methyl ketoneand vinyl ethyl ketone, ketones of the aromatic, arylaliphatic, and cycloaliphatic types having more complex strucstyryl'n-hexyl ketone, cyclohexylidene cyclohexanone, isophorone, and the like, and ketones having more than one functional or carbonyl group, such as CH3COCH2CH2CH2COCH=CH2.

In eifecting the reaction between an nail-11nsaturated ketone and thiocyanic acid by the may be employed.

To liberate thiocyanic acid from these salts, there may be used any strong, non-oxidizing acid over a considerable range of concentration. Acids such as hydrochloric, sulfuric, and phosphoric are particularly suitable and may-advantageously be used at concentrations from 10% to 40%, although weaker and more concentrated so; lutions are also useful. The acid and salt are desirably used in equivalent proportions.

- In carrying out the reaction, the salt and acid are gradually combined or mixed in the presence of an l c-unsaturated ketone and water. The ketone may be stirred with an aqueous solution of the salt and acid added thereto, little by little. On the other hand, the salt or solution thereof may be added gradually to a stirred mixture of an nap-unsaturated ketone and the acid.

lip-unsaturated ketones include aliphatic, aryl- 2, andhomologues thereof, vinyl alkyl ketones,

The ketone may be added directly to asolution of acid or salt in water or in water and an organic solvent, particularly one miscible with water, such as acetone or ethyl alcohol. In the case of solid gr-unsaturated ketones or highly viscous liquid ketones, it is often helpfulto'dissolve the ketone in a suitable organic solvent, such as alcohol or benzene, to facilitate 'better dispersion in the reaction medium.

The method of preparing B-thiocyano ketones according to this invention is illustrated by the following examples.

Example 1 A mixture of 147 parts of mesityl oxide, 160 parts of water, and 121.5 parts of sodium thiocyanate was stirred rapidly at C. while there was added dropwise thereto 150 parts 01 concentrated hydrochloric acid during the course of thirty-five'minutes. After all of the acid had been added, the resulting mixture was heated for twenty minutes longer at 95 C. with constant stirring. It was then cooled and permitted to form layers. The oil layer was separated, washed with water, dried, and distilled in vacuo. The desired product distilled at 96-10'7 C./5 mm. as a pale yellow liquid in a yield of 170 parts, or 72% of theory. Upon redistillation, the pure compound, 2-methyl-2-thiocyanopentanonee4,

'cm-d-cm-co-cn.

- SON boiling at 98-100 C./9 mm., was obtained. It is an almost colorless oil which, upon standing in the air and sunlight, gradually turns reddish. It decomposes upon distillation at atmospheric pressure.

' Example 2 as an almost colorless oil boiling at 105-108' C./1.5 mm.

The ,5-ethy1-3-heptene-one-2 used above is acolorless oil boiling at '77- 79 C./13 mm., ,prepared by condensing diethyl acetaldehyde with acetone in the presence of boiling aqueous barium I hydroxide solution.

To a rapidly stirred mixture of 138 parts of,

phorone, 152 parts of ammonium thiocyanate, and 150 parts of water heated at 95 0., there was gradually added 200 parts of concentrated hydrochloric acid during the course of one hour,

during which timethe reaction temperature was maintained at 95-98 C. The mixture was stirred for an additional half hour at 95 C. after all of the hydrochloric acid had been added. The reaction mixture was filtered hot and an oil layer separated therefrom. This was washed several times with water and dried in vacuo on a steam bath. The residual oil, which amounted to 215 parts, was distilled in vacuo, yielding two main fractions as follows:

(I) The fraction passing over at l20-135 C./5 mm. amounted to 128 parts. Upon redistillation in vacuo, it yielded the pure compound as a pale yellow oil boiling at 104-107 C./1 mm. and having the formula:

at '95" c. The mixture was stirred for thirty minutes longer at 95 C. after all of the hydrochloric acid had been added. The product was washed with water and dried in vacuo on asteam'bath,

yielding 98 parts 0! crude product as a thick oil. This ofl was distilled in vacuo, yielding '76 parts I of 5-ethylA-thiocyano-heptalnone-2,

o mixture was then stirred for an additional twenundergoes partial decomposition unless distilled in small quantities. The pure compound i a pale Example 4 A mixture of 98.5 parts or 5-ethyl-3-nonene-' one-2, 50 parts of water, and 48.5 parts onsodium thiocyanate was heated at 95 C. and stirred rapidly while 60 parts of concentrated hydrochloric acid was added dropwise during the course of one hour. The mixture was then stirred. at 95 C. for twenty-five minutes. The ,product was washed with water and dried in vacuo on a steam. bath.

The residual oil was distilled in vacuo, yielding parts of pure 5-ethyl-4-thiocyano-nonanone-2,

' cmcnionlcnr-dn-cn-cm-c o cm scN as a faintly yellow oil boiling 'at 122-123 C./1 mm.

The 5-ethyl-3-nonene-one-2 usedabove is a colorless oil boiling at l19-123 C./22 mmsprepared by condensing 2-ethyl-hexylaldehyde with acetone in the resence of aqueous barium hydroxide solution.

Example 5 A mixture of 58.5 parts of 3-nonene-one-2, 36.4

parts of sodium triocyanate, and 37 parts of water was heated on a steam bath to C. and stirred rapidly. Concentrated hydrochloric acid (45 parts) was added dropwise to the stirred mixture at 95 C. duringthe course of one hour. The

ty-flve minutes at 95 C. and was finally washed, dried, and distilled in vacuo.

The 4-thiocyano-nonanone-2,

came over between and C./2 mrn. as a pale yellow oil in a yield of 50 parts. Upon redistillation in vacuo, the pure compound boiled at 109-112 C./l.5 mm.

' Example 6 Concentrated hydrochloric acid (70 parts) was added dropwise during the course of fifty minutes to a stirred solution of 105 parts ofcyclohexylidene cyclohexanone, 56.7 parts of sodium thiocyanate, 60 part of ethanol, and 60 parts or water at 90 C. The resulting mixture was then heated for forty-five minutes longer at 90 C. It was mixed with water and an oillayer was separated, washed, and dried-in vacuo at. 95 C. The yield of crude product wa parts. Upon distillation in vacuo, th'e cyclohexylidene cyclohexanone hydrothiocyanate obtained,- having the formula;

yellow oil boiling at -155 0.11.5-2 -mm., having the following constants: 11 1.5473; d9.

Example 7 A mixture of 40 parts of isohexylidene cyclohexanone, 24.3 parts of sodium thiocyanate, 30 parts 01' water, and 30 parts 01 ethanol was stirred at 90 C. while there was gradually added 30 parts or concentrated hydrochloric acid during the course or twenty-five minutes. The mixture was then stirred for forty-five minutes longer at 90 C. and was finally washed and dried in vacuo.

The crude product, amounting to .42 parts, was a clear dark-brown oil containing 10.6% of sulfur by analysis, corresponding toabout an 80% content of the thiocyanate having the formula:

cg. co-cm cn-cm-c on, 0.11. CN CHr-Cfii Upon distillation in vacuo, the product undergoes some decomposition. The pure product is a pale yellow oil boiling at 142 C./1.5 mm.

Example 8 To a clear solution of 138 parts of isophorone. 121 part -of sodium thiocyanate, 121 parts of water, and 121 parts or ethanol, there was gradually added,'with stirring, 150 parts of concentrated hydrochloric acid at 90 C. during the course of fortyminutes. The mixture was then heated for thirty minutes at 90 C. and poured into 500 parts of water. The separated oil layer was removed, washed several times with water,

filtered from a small amount of solid material,

and dried in vacuo at 100 C.

The product obtained was apale-brown thin oil containing approximately 50% by weight of isophorone hydrothiocyanate having the formula:

NCS Cs Upon distillation in vacuo at mm., it almost completely decomposes.

The p-thiocyano 'ketones which are prepared according to the above described procedures are prepared by reacting a ketone having in its structure the grouping RI RI.

trail. I.

" to give the grouping wherein It represents hydrogen or a hydrocarhon-group, including hydrocarbon chains forming cycles. and R" also represents a hydrocarbon group. These compounds are useful as insecticides and as solvents. Thep-thiocyano ketones are relatively stable compounds, resisting hydrolysis in aqueous system and having considerable thermal stability. 1 i

I claim: a

. 1. As a new compound, an addition product .0

. thiocyanic acid and an aliphatic ketone having tion mixture by the action of a non-oxidizing cyano-pentanone-4 which comprises reacting by a double bond between carbon atoms in the capposition, said product being a p-thiocyano ketone.

2. As a new compound, an addition product of thiocyanic acid and mesityl oxide having the formula:

' CHI C-GHr-C 0-011: '03. CN

' 3. As a new compound, an addition product 01 thiocyanic acid and phorone having the formula:

c-cm-c o-cn=c C i ON CH:

4. As a new compound, an addition product or thiocyanic acid and 5-ethyl-3-nonene-cne-2 having the formula:

5. A method for preparing p-thiocyano ketones which comprises reacting by addition at a temperature above room temperature up to about 100 C. a ketone having a double bond between carbon atoms in the c p-position and nascent thiocyanic acid in an aqueous medium, said thiccyanic acid being gradually liberated in. the reaction mixture by the action of a non-oxidizing mineral acid upona salt of thiocyanic acid.

6. A method for preparing p-thiocyano ketones which comprises reacting by addition :at a temperature above 30 C. up to about 100 C. an aliphatic ketone having a double bond between carbon atoms in the l p-position and nascent thiocyanic acid in an aqueous medium, said thiccyanic acid being gradually liberated in the reacmineral acid upon a salt of thiocyanic acid.

. '7. A method for preparing 2-methyl-2-thioaddition at a temperature above 30' C. up to about 100 C. mesityl oxide and nascent thiocyanic acid in an aqueous medium, said thiocyanic acid being gradually liberated in the reaction mixture by the action of a non-oxidizing mineral acid liberated in the reaction mixture by the action "of a non-oxidizing mineral acid upon a salt of thiocyanic acid.

, HERMAN. A. BRUS ON. 

